Generally, a hydraulic excavator, for example, is largely constituted by an automotive lower structure, an upper revolving structure rotatably mounted on the lower structure, and a working mechanism built on the front side of the upper revolving structure to be lifted up and down in relation with swing motions of the upper revolving structure, for example, for a ground excavating operation.
In the case of an excavator as mentioned above, the upper revolving structure is including a revolving frame which is in the form of a strong support structure, and a base end portion of the working mechanism is attached to the front side of the revolving frame. A counterweight is attached to the rear side of the revolving frame as a weight balance relative to the working mechanism. Further, an engine and a heat exchanger are mounted on the revolving frame at positions on the front side of the counterweight. These engine and heat exchanger are accommodated in a machine room which has an engine cover. Furthermore, a cab is built on a left front portion of the revolving frame to provide an operator's room on the front side of the engine cover of the machine room (e.g., see Japanese Patent Laid-Open No. H8-183350).
In the case of the above-mentioned hydraulic excavator of the prior art, a front support member and a rear support member are erected on a left side portion of the revolving frame. Provided between the front and rear support members is a louver having a plural number of stays set at regular intervals in the fashion of grating. The louver serves to enhance the rigidity of the front and rear support members.
By the way, in the case of a small-size hydraulic excavator which is small in gross weight (e.g., smaller than 7 tons), normally the excavator is provided with an engine cover which can be opened and closed, for example, by a servicing worker on the ground at the time of inspection of an engine and a heat exchanger inside. There is little possibility of a servicing worker climbing onto the engine cover.
Accordingly, at the time of cleaning from outside a rear window pane at the rear face portion of a cab, for example, a servicing worker climbs onto a crawler belt of a lower structure instead of the engine cover to reach out his or her hand to the rear face portion of the cab. That is to say, a servicing worker has to perform and continue a cleaning job of the rear face portion of the cab in an instable posture, despite inefficiency of the cleaning job.
In this regard, the above-mentioned prior art employs a louver having a plural number of stays set at regular intervals in the fashion of a grating between front and rear support members on the back side of a cab. In this case, however, a servicing worker who has climbed onto a crawler belt cannot grab the louver like a hand-rail for the purpose of stabilizing his or her posture while performing a cleaning job on the crawler belt.